The invention relates to a multilayer circuit board and a method for manufacturing the same, and more particularly to a method for manufacturing a multilayer circuit board that includes forming a patterned conductive layer which has a submount pattern and a circuit pattern.
It is known in the art that high power chips may generate large amount of heat when working. A circuit board used for mounting the high power chips may be required to have high heat-dissipation efficiency to avoid heat generated from the high power chips from accumulating thereon.
One type of a conventional circuit board, such as Metal Core Printed Circuit Board (MCPCB), has been widely used for mounting the high power chips, especially for mounting LED chips, so that the heat resulting from the high power chips can be efficiently dissipated therethrough. A conventional MCPCB normally has a copper layer serving for conductive traces and soldering pads, a dielectric layer, and a base layer that is usually made of aluminum. Since the dielectric layer has a relatively low thermal conductivity value of about 0.1-0.5 W/mK and is sandwiched between the copper layer and the base layer, it becomes a thermal barrier for heat transfer from the copper layer to the base layer, which results in a decrease in heat dissipation efficiency.
Another type of the conventional circuit board has a structure that includes a plurality of through-holes and a plurality of metal blocks. The metal blocks are inserted fittingly into the through-holes for mounting and heat dissipation of semiconductor chips and/or components. In order to secure the metal blocks in the through-holes, the metal blocks have a diameter or cross-section that is slightly greater than those of the through-holes, which causes undesired stress in the circuit board. In addition, since the metal blocks are formed using mechanical machining techniques, control of machining the same may be relatively difficult and a high precision of the metal blocks may be difficult to achieve when the size and the thickness of the metal blocks are small. Moreover, since the metal blocks are inserted into the through-holes using a pick and place machine, there may arise a precision problem for alignment of the metal blocks with interconnections that are subsequently formed on the circuit board for connecting the metal blocks to the semiconductor chips and/or components, such that misalignment between the metal blocks and the interconnections tend to occur.